1. Field of the Invention
The present invention relates to a hydrogenated modified polymer and a process for producing the same as well as a composition containing the same. More particularly, the present invention relates to a hydrogenated modified polymer which can afford a molded body excellent in improvement in the impact resistance, the strength and the adherability as well as appearance, and a process for producing the same as well as a composition containing the same. And the present invention relates to a composition which can afford a product excellent in the balance among the flame retardancy, the tensile strength, the tensile extension, the heat resistance, the characteristic at low temperature, the insulation property, the pliability and the like, a covered material for an electric cable used in an instrument, a harness for automobile or the like, an industrial material such as an insulating tape and the like.
2. Prior Art
Although polymers have hitherto been used in many materials, since almost of them are not a single polymer in respects of the strength, the heat resistance, the impact resistance, the adherability, the cost and the like, the polymers have been used as a multicomponent polymer or a composition containing the polymer and a reinforcing agent such as a filler, and the like. For example, a hydrogenated block copolymer obtained by hydrogenation of a block copolymer consisting of conjugated diene and aromatic vinyl hydrocarbon has the comparatively high compatibility with nonpolar resins such as a polyolefin resin and a polystyrene resin, or nonpolar rubbers such as ethylene/propylene rubber and, therefore, a variety of compositions are prepared and used widely.
However, since the previous hydrogenated block copolymer has the low compatibility with polar resins such as PET, ABS, nylon and the like, in order to maintain such physical properties that can stand the use, it is necessary to introduce a polar group to the hydrogenated block copolymer. As a method of introducing such polar group, for example, there are a method of grafting a polar group-containing monomer as described in JP-B-2-62131, JP-B-3-12087 and JP-B-2-15569. Although this grafting method can add a polar group at an arbitrary amount, there are problems about treatment of an unreacted modifier, molecular cleavage of a polymer, cross-linking and the like and, furthermore, there is a problem that it is difficult to obtain the desired physical properties with the better reproductivity. In addition, an end-modifying method described in JP-B-4-39495 has a problem that the sufficient weather resistance of a molded body can not be obtained.
Because of the excellence of an olefin-based polymer (resin) in both physical and chemical characterizations, it is widely used as household articles and industrial material, for example, film, sheet, pipe, vessel, electric cable, cable and the like are produced by the way of injection molding, extrusion molding and the like. An olefin-based polymer is generally easy to burn and some methods of making it hard to burn the polymer are opened.
It is known that the most general method is to use a halogen-based flame retardant for the olefin-based polymer. Although the above-mentioned flame retardant shows a flame-retardant effect with a small amount, corrosive or noxious gas may generate when burning.
Recently there have been proposed a flame retardancy polypropylene resin composition containing no halogen-based flame retardants, for example in JP-A-2-263851. Phosphorus-based flame retardant is contained in this composition, however, it is necessary to avoid bleeding on the basis of the hygroscopic. By formulating an olefin-based synthetic rubber and a silane coupling agent, a constant improvement of avoiding bleed, it is not enough and is not always satisfied from a viewpoint of physical properties such as flexibility and pliability, pollution-free and environmental harmony.
A flame retardancy polypropylene resin composition containing propylene homopolymer, ethylene/propylene copolymer rubber, bis(2,3-dibromopropyl)ether of tetrabromobisphenol S and antimony trioxide is indicated, for example in JP-A-61-183337. In this composition bis(2,3-dibromopropyl)ether of tetrabromobisphenol S is used as a flame retardant and it has doubt of environmental hormones. It is not always satisfied from a viewpoint of environmental harmony. And since this composition contains an ethylene-propylene copolymer rubber, a constant improvement in the impact strength is observed, but in the case the composition is used for a covered material for an electric cable, it was not necessarily satisfied about the pliability demanded at the time of wiring and an assembly.
Further, a hydrate of an inorganic metal compound such as aluminum hydroxide, magnesium hydroxide and the like as a pollution-free and environmental harmony type flame retardant is recently proposed (for example in JP-A-10-279736). When a flame retardancy composition containing such hydrate of an inorganic metal compound is used, it is necessary that the content is increased in the composition, but too much content may lead to lower the mechanical property, tensile strength in particular and molding processability. For the purpose of improving this problem, a flame retardancy composition containing a styrene-based thermoplastic elastomer modified with a carboxylic acid or an acid anhydride, a metal hydroxide metal and the like but a halogen-based flame retardant is proposed (for example in JP-A-7-165997, JP-A-2000-340034). Using the styrene-based thermoplastic elastomer modified with a carboxylic acid or an acid anhydride has a problem about treatment of an unreacted modifier, molecular cleavage of a polymer, crosslinking or the like, and has a difficulty of obtaining the desired physical properties with the better reproductivity, since it is made to graft-polymerize a modifier such as maleic anhydride to a styrene-based thermoplastic elastomer in the presence of a peroxide. And using the modified styrene-based thermoplastic elastomer is effective for progress in affinity between the elastomer and an inorganic flame retardant, improvement in the tensile extension, the heat resistance, the characteristic at low temperature and the pliability is not enough because of a little entanglement with an olefin-based polymer and a little interface reinforcing effect between the olefin-based polymer and an inorganic-based flame retardant.